By Paul Cresswell
The world’s obsession with cleanliness has been identified as a cause of the rising rate of depression, according to scientists.
Scientists have long blamed our sterile environment for increases in asthma and allergies, as some of the bacteria necessary for strengthening the immune system are routinely cleared away, resulting in our bodies over-reacting to dust and pollen, resulting in an allergy.
But recent research has gone one step further; claiming this bodily over-reaction may also impair the brains ability to produce certain chemicals responsible for good mental health, including serotonin, leading to depression. The research is backed up by the fact that rates of depression are far higher in the western world compared to poorer nations as westerner’s immune systems are less trained to deal with bacteria.
Researchers in Atlanta, Georgia have tested this theory by recruiting a group of 27 patients taking drugs to treat Hepatitus C, which causes a similar over reaction in the body. Researchers believe certain reactions cripple the brain’s ability to produce chemicals responsible for mental well being – including the so called ‘happy hormone’, serotonin.
Dr Andrew Miller, a scientist involved in the research, said: “We believe the immune system is causing depression. As people develop and grow up, their immune system develops. If they are exposed to more bacteria and parasites, they are better able to control the inflammation. Nowadays, people’s environments are much cleaner and hygienic so our immune systems never really learn how to deal with infectious agents. We are overactive because our immune system has not been trained.”
The researchers, whose study was published in the journal Molecular Psychiatry, are now testing whether anti-inflammatory drugs could be used to treat depression.
But this method clashes with another research project conducted by Rockefeller University, New York. This separate research suggests anti inflammatory painkillers such as aspirin and Ibuprofen, as well as other painkillers such as paracetamol, could prevent anti depressants such as Prozac from working properly.
Selective Serotonin Reuptake Inhibitors or SSRI’s are prescribed to millions every year, many of whom complain these pills are not effective. Rockefeller scientists believe they now know why. The researchers said it was not clear why the pills had this effect, but warned their findings could have ‘profound implications’ for patients.
The US research team gave anti depressants to mice with depression and monitored for behaviour changes. Half the sample of mice were also given painkillers.
Their tests revealed that SSRI’s worked less well when the painkiller was also in the animals’ system. Other types of anti depressants, other than the SSRI’s, were not affected, according to the journal ‘Proceedings of the National Academy of Sciences.’
The same team found a similar effect in humans, after studying medical records. They report that anti depressants were effective in less than 40% of cases involving patients also taking aspirin-like painkillers, compared to 54% for others.
The researchers also report that the impact on pensioners (seniors, if you’re American) will be particularly severe as depression in this age group also raises the risk of Alzheimer’s disease, and if the depression isn’t correctly treated in Alzheimer’s patients, the illness can progress more rapidly.
Dr Paul Greengard said: “Many elderly patients suffering from depression also have arthritic or related diseases and, as a consequence, are taking both anti depressant and anti inflammatory medications together, meaning that physicians should carefully balance the advantages and disadvantages of continuing anti inflammatory therapy in patients being treated with anti depressant medications.”